Calprotectin and spondyloarthritis

Faecal Calprotectin for the Diagnosis of Bowel Inflammation in Patients With Rheumatological Diseases: A Systematic Review

BACKGROUND AND AIMS

Endoscopic and histological gut inflammation are present in half of patients with ankylosing spondylitis [AS] or spondyloarthritis [SpA]. We performed a systematic literature review on the use of faecal calprotectin [FC] in patients with rheumatic diseases.

METHODS

Searches of the PubMed, Web of Science, and Cochrane Library databases were performed up to September 2019 to identify all studies including adult patients with confirmed diagnosis of SpA or AS.

RESULTS

Seven studies met the inclusion criteria: six prospective observational studies and one retrospective observational study. Study populations consisted of SpA patients in four studies and AS patients in three studies. In six studies, an ELISA test was used for FC levels and in one case, a semi-quantitative assay was adopted. In all included studies, patients with SpA or AS had elevated FC levels, ranging from 21.2% to 70.7% of patients. In six studies, patients with increased FC levels had macroscopic mucosal inflammation, ranging from 11% to 80% of cases. Four studies highlighted the presence of microscopic alterations in patients with high FC levels, ranging from 41.7% to 100% of patients. An FC cut-off level predicting the inflammatory bowel disease [IBD] occurrence was found in two studies: 266 mg/kg and 132 mg/kg, with sensitivity and specificity of 100%, 78.7% and 66.7%, 76.9%, respectively.

CONCLUSIONS

Faecal calprotectin is a useful and non-invasive marker to predict IBD in patients with SpA or AS. Gut histological and macroscopic mucosal inflammation were found in up to 100% and 80% of rheumatological patients with increased FC levels.

Discriminating Value of Calprotectin in Disease Activity and Progression of Nonradiographic Axial Spondyloarthritis and Ankylosing Spondylitis

It has been controversial whether ankylosing spondylitis (AS) and nonradiographic axial spondyloarthritis (nr-axSpA) are separate or different phases of radiographic progression. We determined that serum calprotectin level (ng/ml) was higher in AS (15.30 ± 6.49) and nr-axSpA (17.76 ± 8.59) patients than in healthy individuals (7.40 ± 2.67). No difference was observed in calprotectin level between these two groups. Elevated calprotectin was positively correlated with ESR, CRP, BASDAI, and ASDAS as well as SPARCC scoring and had no correlation with BASFI and mSASSS. No correlation was observed between calprotectin and Wnt/β-catenin pathway markers. Serum calprotectin can be used as a marker for inflammation in both nr-axSpA and AS, while it does not contribute to the discrimination of AS and nr-axSpA. Calprotectin-mediated inflammation was not correlated with principle effectors of Wnt/β-catenin pathway, indicating that inflammation and bone fusion might be separate processes of the disease.